Granata K P, Marras W S
Biodynamics Laboratory, Ohio State University, Columbus, USA.
Spine (Phila Pa 1976). 1995 Apr 15;20(8):913-9. doi: 10.1097/00007632-199504150-00006.
Measured trunk muscle activity was employed in a biomechanical model to determine the influence of including or neglecting muscle coactivity on predicted spinal loads.
The purpose of this investigation was to examine the influence of muscle coactivity on spinal load.
Electromyographic patterns in the trunk musculature have demonstrated significant levels of cocontraction during lifting exertions. Biomechanical analyses of musculoskeletal loading are often mathematically constrained from including muscle coactivity. Models that attempt to include coactive behavior are complex and difficult to implement.
Electromyographic data were collected from five trunk muscle pairs while subjects performed dynamic lifting exertions. A validated, electromyographically assisted biomechanical model was used to compute relative muscle force, lifting moment, and spinal load. Results were generated and compared from analyses that included from one to five simultaneously active muscle pairs.
Trunk extensor muscles generate lifting moments as much as 47% greater than the applied lifting moment to offset flexor antagonism. Analyses that neglect muscle coactivity during dynamic lifting exertions may underestimate spinal compression by as much as 45% and shear forces by as much as 70%.
The level of coactive spinal loading is significantly influenced by the weight of the lifted load as well as trunk extension velocity. Muscle coactivity significantly influences the modeled load in the lumbar spine during lifting exertions and should be considered if an accurate measure of spinal loading of desired.
在生物力学模型中采用测量的躯干肌肉活动，以确定纳入或忽略肌肉共同激活对预测脊柱负荷的影响。
本研究的目的是检验肌肉共同激活对脊柱负荷的影响。
躯干肌肉组织的肌电图模式显示，在举重过程中存在显著水平的共同收缩。肌肉骨骼负荷的生物力学分析在数学上往往受到限制，无法纳入肌肉共同激活。试图纳入共同激活行为的模型复杂且难以实施。
在受试者进行动态举重时，从五对躯干肌肉收集肌电图数据。使用经过验证的肌电图辅助生物力学模型来计算相对肌肉力量、举力矩和脊柱负荷。对包含一到五对同时激活的肌肉的分析结果进行生成和比较。
躯干伸肌产生的举力矩比施加的举力矩大47%，以抵消屈肌的拮抗作用。在动态举重过程中忽略肌肉共同激活的分析可能会低估脊柱压缩多达45%，剪切力多达70%。
脊柱共同激活负荷水平受举起负荷的重量以及躯干伸展速度的显著影响。肌肉共同激活在举重过程中对腰椎模型负荷有显著影响，如果需要准确测量脊柱负荷，则应予以考虑。
